Healthy aging is associated with a multitude of structural changes in the brain. These physical age-related changes are accompanied by increased variability in neural activity of all kinds, and this increased variability, collectively referred to as “neural noise,” is argued to contribute to age-related cognitive decline. In this study, we examine the relationship between two particular types of neural noise in aging. We recorded scalp EEG from younger (20–30 years old) and older (60–70 years old) adults performing a spatial visual discrimination task. First, we used the 1/f-like exponent of the EEG power spectrum, a putative marker of neural noise, to assess baseline shifts toward a noisier state in aging. Next, we examined age-related decreases in the trial-by-trial consistency of visual stimulus processing. Finally, we examined to what extent these two age-related noise markers are related, hypothesizing that greater baseline noise would increase the variability of stimulus-evoked responses. We found that visual cortical baseline noise was higher in older adults, and the consistency of older adults' oscillatory alpha (8–12 Hz) phase responses to visual targets was also lower than that of younger adults. Crucially, older adults with the highest levels of baseline noise also had the least consistent alpha phase responses, whereas younger adults with more consistent phase responses achieved better behavioral performance. These results establish a link between tonic neural noise and stimulus-associated neural variability in aging. Moreover, they suggest that tonic age-related increases in baseline noise might diminish sensory processing and, as a result, subsequent cognitive performance.

健康老龄化与大脑中的多种结构变化有关。这些与年龄相关的身体变化伴随着各种神经活动变异性的增加，而这种变异性的增加，统称为“神经噪声”，被认为是导致与年龄相关的认知能力下降的原因。在这项研究中，我们研究了衰老过程中两种特定类型的神经噪声之间的关系。我们记录了执行空间视觉辨别任务的年轻（20-30 岁）和年长（60-70 岁）成年人的头皮 EEG。首先，我们使用 1/ f像 EEG 功率谱的指数，神经噪声的一个假定标志，用于评估基线在衰老过程中向噪声状态的转变。接下来，我们检查了视觉刺激处理的逐次试验一致性与年龄相关的下降。最后，我们检查了这两个与年龄相关的噪声标记在多大程度上相关，假设更大的基线噪声会增加刺激诱发反应的可变性。我们发现老年人的视觉皮层基线噪声较高，老年人对视觉目标的振荡 alpha (8-12 Hz) 相位响应的一致性也低于年轻人。至关重要的是，基线噪音水平最高的老年人也有最不一致的 alpha 相位响应，而具有更一致的相位反应的年轻人则获得了更好的行为表现。这些结果建立了强直性神经噪声与衰老中与刺激相关的神经变异性之间的联系。此外，他们认为与年龄相关的基线噪音的强直性增加可能会削弱感觉处理，从而降低随后的认知能力。